A safety razor generally includes a handle and a blade unit carried on the handle and including at least one blade with a sharp cutting edge. In the course of shaving the blade unit is applied against the skin and the blade or blades are moved across the skin so that the sharp cutting edges engage and cut through the hairs protruding from the skin.
The blade unit can be fixed on the handle with the intention that the entire razor should be discarded when the cutting edges have become dull and no longer capable of providing a comfortable shave. Alternatively the blade unit may be removably mounted on the handle so that the blade unit can be replaced by a new blade unit when the sharpness of the blades has diminished to an unacceptable level. Replaceable blade units are often referred to as shaving cartridges.
The majority of safety razors currently marketed are operated and used entirely manually. Nonetheless electrical devices can be incorporated in safety razors. For instance, it is known to include an electrically driven vibration mechanism which is operable to vibrate the razor, since it has been observed that such vibration can have a beneficial effect on razor performance. A simple and convenient vibration generating mechanism consists of an electric motor with a weight mounted eccentrically on its output shaft. The vibration mechanism and a battery for providing electric power to the motor can be conveniently housed in the razor handle. Examples of previous proposals for such razors are those described in U.S. Pat. No. 3,611,568, U.S. Pat. No. 5,299,354, U.S. Pat. No. 5,214,851, and U.S. Pat. No. 5,046,249. In U.S. Pat. No. 6,481,104B1 there is disclosed a safety razor housing including a vibration mechanism and a tight emitting diode which is illuminated when the vibration mechanism is turned on. A vibrating razor described in EP-A-0885698 includes a power meter or indication to indicate the battery power remaining and/or to indicate when a new battery is needed.
A vibration mechanism can be adapted to vibrate only one or more selected components of the blade unit, such as the guard which contacts the skin in front of the blades, or one or more blades, and the vibration may be directional, for instance directed lengthwise of the blades to encourage a slicing cutting action or transverse to the blades. Another possibility is for an element to be vibrated in a direction generally perpendicular to the skin surface being shaved. The vibration mechanism may incorporate a piezoelectric device for producing the vibrations, instead of a motor for rotationally driving an eccentric weight.
Other forms of electrical device besides vibration generators can be included in wet razors, some examples of such devices being: (i) heating devices for heating one or more blades or other components of a blade unit which contact the skin during shaving, such as Peltier devices or electrical resistance or ohmic heating devices; (ii) dispensing devices for delivering a shaving enhancement product to the skin and which may be activated by operation of a motor driven pump or by operation of a valve having an electrically controlled actuator, shaving enhancement products which can be delivered at a safety razor blade unit during performance of a shaving stroke including those with the qualities and properties mentioned in our patent application No. WO 00/47374, the contents of which are incorporated herein by reference in their entirety; (iii) conditioning devices to prepare the skin and/or hairs ready to be cut by the blades, such as a roller mounted in the region of the guard of the blade unit and adapted to be rotated about its axis for encouraging hairs tying against the skin to stand up for cutting; iv) illumination devices for illuminating an area of skin being shaved; and v) actuators for adjusting the blade unit in accordance with prevailing shaving conditions detected by a sensor.
In EP-A-0906814 and U.S. Publication No. 2002/0189102 there are described razors with force sensors and electronically activated indicates to signal that blade replacement is necessary. There is described in GB-A-2258922 a personal care apparatus such as a hair dryer or electric toothbrush that is mains operated and includes an indicator to show that the apparatus is connected to the AC source. There is a capacitive sensor in the handle so that the apparatus is activated as soon as it is picked up in the hand.
When there is an electrical device included in a safety razor it is often convenient for the device to be operated by a replaceable or rechargeable electric storage battery that can be housed within the razor handle. To conserve battery power it is preferable for the electrical device to be disconnected from the battery during periods when the razor is not in use. In some cases it may be immediately obvious to a user when connection between the electrical device and battery is established, such as if the device is a vibration generator which is set into operation as soon as the electrical connection to the battery is made, but there may be other examples where it is not so obvious.